It is known that a protective layer, an "artificial skin" can be produced on skin and mucous membrane. Such a protective layer may be desirable in the case of burns, bed-sores or to cover an operation wound, for instance. A solution of a polymer-forming substance in a solvent may be sprayed on the skin, for instance, so that a plastic film is formed when the solvent evaporates. One drawback with this procedure is that the organic solvent causes stinging and probably damages the tissues.